The present invention relates to a hinge unit for a seat, particularly for a seat of a power vehicle.
Units of this general type are known in the art. A known hinge unit includes a fixed hinge element associated with a seat part of a seat, and a pivotable hinge element associated with a back part of the seat and pivotally connected with the seat part. The fixed hinge part has a recess in its upper region, and a two-sided catch lever is pivotally mounted on the pivotable hinge part and has a locking projection abutting against an abutment at one end of the recess, and a heavy arm which urges under the action of its own weight the locking projection to its free position. The above mentioned catch lever is angular, and its heavy arm has an abutment edge which together with a sliding face associated with the fixed hinge element turns back the engaging projection of the catch lever during the forward swinging of the back part from abutment of the fixed part. The heavy arm of the catch lever is thereby so designed and arranged that the force of inertia acting upon the catch lever holds the locking projection of the catch lever in its ready-to-lock position whereby in these cases the locking projection comes into contact against the abutment and prevents forward swinging of the back part. When, however, the back part is moved slowly, the force of inertia on the catch lever is negligibly small, so that the catch lever can turn over the sliding surface out of its ready-to-lock position. In vehicle seats in which the back part must be swung forwardly in order to make accessible the rear portion of particularly two-door cars, this construction possesses a considerable advantage, inasmuch as it allows a one-hand operation for forward swinging of the back part. In seats whose locking must be released by an additional lever, the back part can be adjusted conveniently only with both hands in such a manner that one hand releases the catch element whereas the other hand swings the back part. This is particularly inconvenient when packages or other objects must be held in one hand. The hinge unit operable by one hand possesses, however, the disadvantage that the locking projection in each case gets out of its ready-to-lock position when the back part is slowly moved forwardly. Because of this, there is a danger for the user of a vehicle seat when passengers occupying the rear part of the car support themselves during travel against the back part.